Integrated circuit (IC) packages are often used for applications in which power is distributed among one or more IC dies. Power is commonly routed to an IC die in an IC package through a post-passivation interconnect (PPI) structure that includes multiple redistribution layers (RDL).
As IC applications become increasingly complex and depend on increasing clock speeds and decreasing power supply voltages, sensitivity to noise such as simultaneous switching noise (SSN) and ground bounce noise (GBN) increases. Performance of filters used to suppress such noise is sometimes gauged by an S21 parameter, also referred to as a transmission coefficient, which indicates the amount of power transmitted by the filter at a given frequency.